Whenever a rotating power source such as a motor, engine or an intermediate device such as a clutch, transmission or gear box must provide energy to a power-consuming load, there exists the problem of matching and aligning the shafts of the power source to the power consuming load. For purposes of discussion any power source or power load will be referred to as a power device hereinbelow. One way in which power is transmitted from a power source to a load is by rotating shafts arranged end-to-end in a coupled relationship. These shafts are generally retained in bearings which allows essentially friction-free rotation of the shafts. Most bearings are easily damaged if subjected to any side-to-side pressure or stress. Such stress may arise if the two coupled shafts are not in perfect alignment (i.e., the two shafts are not coplanar as well as coaxial). In addition to excessive bearing wear or, in extreme cases, destruction of the bearings, unaligned operation generally results in chatter or vibration which may effect the functionality of the apparatus of which the motor/coupling/load subsystem forms a part. Even if vibration or chatter does not degrade system performance, it is annoying and may cause the apparatus to seem subjectively inferior to a quieter competitive product. In an ideal power coupling housing it is important that means be provided to compensate for small variations in power devices, shafts, coupler or in the housing structure itself, any of which may cause misalignment.
In addition, the coupler must sometimes also provide support to one or more power devices which necessitates a sturdy, reasonably rigid design.